Combined recorder and reproducer



July 26, 1949. s. A. SCHER BATSKOY 2,477,144

COMBINED RECORDER AND REPRODUCER 2 She'ets-Sheet l MAGAZINE NO 3 Filed Feb. 18, 1943 M0 TOR Patented July 26 1949 UNITED 1 STATES PATENT OFFICE Serge Alexander Scherbatskoy, Tulsa, Okla. Application February 18, 1943, Serial No. 476,368

.My invention relates to sound recording and reproducing systems and more particularly to magnetic recorders and reproducers known as telegraphones in which, as is well known, the signals are recorded by varying the magnetic condition of a moving magnetic member and are reproduced by causing such a magnetized member to vary the induction in a suitable translating device. y

The object of my invention is to provide a novel method and apparatus of this kind and in general to improve the operation of such a recording and reproducing system.

My invention relates particularly to a magnetic recorder and reproducer adapted to'record longitudinally on extremely thin wire. The advantag'es of the longitudinal type of magnetic recording on thin wire are well known and are primarily due to the fact that the recorded magnetic impulses are impressed upon the wire in a manner which is symmetrical with respect to the longitudinal axis of the wire and consequently precautions against twisting and turning of the wire are not required either for recording or reproducing.

While magnetic recorders and reproducers are old and well known, they have never been used commercially to an extent comparable to the use of phonographs or film recording. There are a number of reasons for this, the more important of which are probably due to the fact that satisfactory quality of reproduction and satisfactory length of duration of the recorded program was possible only with quite voluminous apparatus using a large amount of magnetic Wire and tape which occupied considerable storage space compared to other methods of recording such as film or phonograph disc.

In accordance with the general features of this invention certain engineering requirements are necessary regarding the size and general arrangement of the elements used with particular reference to the size of the wire. It is required that the wire be sufiiciently large to provide at each instant a magnetic moment that is capable of overriding the spurious magnetic moments generated by a stray extraneous field-and that is sufiiciently large so that its statistical fluctuations are small in comparison. It has been demonstrated that these requirements can be met by extremely thin wire of the order of /1000 of an inch thick and it-has been demonstrated that the use of such wire ofiers numerous important ad'- vantages, the main one of which is compactness of the storing mechanism and consequent adaptability'of this system to the recording of long 9 Claims. (01. 179-1002) continuous messages. It has been demonstrated that the limit to the thinness of the wire used is not caused by electric or magnetic considerations, but is dueto the mechanical difficulties involved in the handling and threading of the extremely thin wire. 7

An important feature of my invention consists in providing a removable and compact cartridge type container which will include the magnetic wire in combination with a winding mechanism and the element for impressing a magnetic field upon the wire. It will become apparent from the further description that the full advantages of the longitudinal type of magnetic recording on wire of small diameter cannot be realized without the use of the proposed cartridge type container. I propose to use wire of extremely small diameter and to provide the container that is dust tight and permanently enclosed. The wire contained in it shall be used over and over again without removing the wire from the container and without ever rethreading thev wire through the recording head and the erasing head. The advantages of this arrangement are that an extremely long message can be recorded and stored within a sin-' gle magazine having relatively small dimensions. For example, in a magazine of 3" by 7" by 1" dimensions by using the principle of my invention it is possible to record a message lasting one-half hour. This is more economical of space than any prior arrangement of magnetic recording and actually compares very favorably with the most economical recording means, such as recording on film or recording on a phonograph disc.

Another object of my invention is to provide means for impressing a concentrated magnetic field on the wire. Such a concentration of mag:- netic field in the small space immediately surrounding the wire is accomplished by means of an element hereinafter referred to as the record-, inghead. The recording head consists of a high permeability magnetic core that provides an entirely closed magnetic circuit with the exception of a small air gap. A winding is provided around the magnetic core and the said winding receives the signal currents and produces in the magnetic core a magnetic fiux varying in accordance with the message to be recorded. Furthermore, the core is provided with a small hole parallel to the direction of magnetic fiux and crossin the air gap. The magnetic wire on which it is desired to record a message passes through this hole in a manner such that the wire is entirely shielded from the magnetic field generated by the core except at the point where the wire traverses the 3 air gap. The magnetic circuit is arranged so as to consist entirely of high permeability material except for a single air gap mentioned above.

Further objects of my invention will become apparent in the description of my invention and in the enclosed drawings. In the drawings:

Fig. 2 illustrates the general arrangement of a speech recording and reproducing mechanism and shows various elements thereof.

Fig. 1 shows an exterior View of the speech recording and reproducing device.

Fig. 3 shows an exterior view of the removable magazine which constitutes one of the elements:

of the device illustrated in Fig. 1.

Fig. 4 shows a cutaway rearview of the removable magazine showing the Working. parts,

Fig. 4A shows a cross section of the. recording head.

Fig. 4B shows a view of the flux concentrating arrangements.

Fig.4C shows a cross section of the erasing coi Fig. 5 shows. the general wiring diagram ofv the magnetic recorder. Referring now more particularly to the draw-v iIlES. the arrangement illustrated in Fig. 4 designated by the numeral l shall be designated hereafter. as removable magazine. The removable magazine contains drums II and [2. which are drivenby shafts Band. [4 and are provided with disengageable clutch members l and 16,. These clutchmembers makeit possible to engage or disengage the shafts l3; and 4. with the shafts I1. and I8 andcl utchmembers I5a and 16a respectively shown on the master station illustrated on R g-.

Referring now to. Fig. 2, shafts I1. and I8 are provided with pulleys 9 and 24 which are connectedby abelt 22 and are driven from the drive pulley l9 which in turn is driven by the motor 2 3, the motor 23. being preferably of thesynchronous type and being arranged through the mechanism just described to drive the drums. [JV-and l2shown on Fig. 4. Themechanism just described consisting of a synchronousrnotor 23', and the drive pulleyand' belts, and also certain amplifying and transducing mechanisms that shall be described later, are all contained in a housing 24, and con.- stitute a master unit adapted'to receive the interchangeable cartridge Hl. The interchangeable cartridge "land the master unit 25 are provided with suitable plugs which are arranged to make the proper electrical connection required'betweenthe master unit 25 shown on Fig. 2'and the magazine H)- shown on Fig. 4; The plugs are designated by the numerals 1M and I02 on both thedrawings of Fig. 2 and Fig. 4. In addition to providing the necessary electrical connection these plugs are arranged to couple the two units with the required mechanical rigidity so that when in place the magazine lobecomes an integral part of the whole mechanism.

Fig. 1 illustrates a general exterior view ofthe master unit with the removable magazine designatedby the numeral ID in place and Fig. 3 represents a view of the removable magazine lflwith' the plugs I0! and "Hand clutch members! 5 and I6 "projecting from the surface.

With-reference now to Fig. 4, numerals I I and i2 designate the drums which are used both to drivethe wire and to store the wire. The wire itself isdesignated by the numeral 32 and is arranged to pass from the storage drum l2 through the erasingmechanism 33 and through the recording head 35 andonto the storage and v drive drum II. The erasing device 33} consists essen:

tially of a coil of wire wound on an axis coincident with the axis of a small cylindrical hole 36 through which the wire passes. The winding 31 is wound on a bobbin 38 which is preferably made of Bakelite or wood or some other non-magnetic material. The recording head 35 consists of a high permeability core 40 which is made of a series of thin laminations 4| insulated one from the other. The winding 42 is wound around an axis that; coincides with the position occupied by the wire 32 as it passes through the hole43provided in the high permeability core 40. The single air gap in the magnetic circuit is shown in cross sectioninFig. 4A. andwithin that air gap is placed a flux concentrating arrangement which is also illustrated in this figure. It is apparent that for satisfactory performance the length of the air gap bears relationship to the speed of the wire and. to. the highest frequency that it is desired to record. With these considerations in mind the length of the air gap shouldbeof the, order ofthe wave length of thehighest frequency thatit' is desired to record. For example, if the highest frequency tobe recorded: is 3000. cycles and the speed of the wire is. 3 feet per second then the length ofthe air gap should, be of the. orderof /1 00 of'aniinch. V

Referring now; more particularly to Figure 4A, as mentioned previously, the recording head 35 is provided with. a. single air gap. In. order. to concentrate the flux asimuchas possible intothe region occupied by the wire, a special flux concentrating arrangement is" used and designated by the numeral 44. With further reference to Fig. 4A, numeral 40' designates the high permeability, material which constitutes the magnetic circuit, 42 designates the winding and 43' the hole through which the'wire passes, 63 designates. two tubularpole pieces'made of high permeability materialwhich are designated to concentrate the flux into the region occupied by the wire. Numeral'fiddesignates a brass (or Bakelite or other non-magnetic material) spacing arrangement which servesto separate the" pole, pieces 53' one from the other and provide anaccurate alignment of the magnetic-circuit:

Fig. 43* illustrates the flux concentrator separately; Numeral 53' designates the high'permea bility tubular pole pieces and numeral 64' designates the brass or: Bakelite block" that" serves to" alignthepole piece accuratelyi Numeral-43 indicates the hole throughwhich the wire is passed. Fig.- 46 illustrates-a cross section through the erasing coil-whichhas been designated as 33 on Fig; 4' and'numeral 38* designates the Bakeliteor' other non-magnetic material bobbin andnumeral' 31 indicates-the winding which is-wound" around the axis 15. 36 indicates the hole through which thewire passes.-

Fig. 5 illustrates the electrical'wiring diagram of the arrangement" illustrated on the previous figures. An important part of-thearrangement is theprovision' of-the plugs which are arrangedto connect and disconnect the apparatus housed within the-magazine-from the apparatus housed withinthe master unit, numeral I01 indicates the plugs which-are'arranged to connect and disc'onnecttherecording-head circuit and the apparatus located within the master unit and numeral I02? designates the plugs; used" toconnect and disconnectthe erasing coil with theapparatus locatedwithin the masteriunit: Another important' partofthe. circuit is the switch arrangement. which. consists of, the. double .pole. switches 7510x104; I05,v I05.andJllTalllofthese switches sigma-1144 are arranged to be controlled by a single lever so that when the lever is in the record.position the switches I03 to I01 are all in the up position as indicated by the solid arrows in Fig. 5. When the switch is placed into the "reproduce position all the switches are in the down position which corresponds, to the dotted lines shown on Fig. 5. Assumenow that the switches are in the up position indicates by the solid arrows and with further reference to Fig. 5 the operation is as follows Sound waves impinge upon the electrodynamm loud speaker, I08, This loud speaker is arranged to operate satisfactorily either as a loud speaker or as a microphone. When it operates as a microphone the sound waves impinge upon the dia phragm and cause motions in the electrodynamic transducing mechanism which generate electrical currents that are representative of the sound waves. Usually, when a loudspeaker is operated in this manner, i. e., as a microphone, its frequency characteristic is unsatisfactory and requires equalization in order to improve the quality of the reproduced sound. Therefore on Fig. 5the speech currents generated by the loud speaker I08 are impressed through the switch I03 on an equalizer I09 which serves to improve the quality of reproduction in a manner that is well known in the art. After passing through the equalizer the speech currents are impressed through the switch I04 on to the amplifier H0. The output of the amplifier is impressed through the switches- I05 and I06 and the plug IOI. on to the recording head 35. In the recording head alternating magnetic fields are impressed upon the wire 32 which are a reasonably exact facsimile of the sound waves that originally impinged upon the .diaphragm of the loud speaker I08. Before the wire 32 passes through the recording head 35 it is demagnetized by passing through the demagnetizing coil 33. This demagnetizing coil is energized with a high frequency alternating current which is generated by the oscillator H4 and which is impressed on the demagnetizing coil through the switch I01 and the plugs I02. In the arrangement shown (switches in the up position) the wire 32 therefore is demagnetized first in the coil 33 and then passes through the recording head 35 in which alternate magnetic field is generated which represents the speech.

Assume now that the switch is in the down.

position, i. e., the switches I03, I04, I05, I06, I01 occupy the position shown by the dotted lines on Fig. 5. This corresponds to the reproduce condition and the operation of the circuit is as follows:

The oscillator I I4 is now disconnected from the erasing coil 33 and the erasing coil therefore is not energized and the wire in passing therethrough retains whatever magnetism that existed in it. The wire now passes through the recording head 35 which responds to the magentic field generated by the wire and produces a voltage across the winding of the recording head which is approximately proportional to the rate of change of the magnetic flux. This voltage is impressed across the plug IOI and through the switch I06 is impressed across the terminals of the equalizer I20. This equalizer serves essentially as an integrator such an integrator has been previously described in U. S. Patent No. 2,099,536 and reference is made thereto, The purpose of this integrator is to produce a voltage at its out-. put which is substantially proportional to the integral of the input and consequently which is substantially proportional to the flux enerated in the recording head 35 rather than to the rate of changeof flux therein. The output of the equal-.- izer I20 is impressed through the switch I04 onto the input of amplifier H0 and the output of the amplifierv I I0 is connected to the switch I05 and I03 onto the loud speaker I08 which is arranged to transduce the electric current into audible sound.v The operation of the circuit therefore is such that the loud speaker I08 generates a sound which is substantially a facsimile of the magnetic flux generated in the recording head 35.

I claim:

1. In a combined recorder-reproducer a removable magazine, said magazine comprising record spools with a windable magnetizable element and recording-reproducing head mounted in operative relation to said element, a housing adapted to receive said magazine and comprising a driving means engageable into said spools, an electromechanical transducer, two electrical networks difiering in characteristics one from the other and having their output terminals connectable to said recording-reproducing head, and an electrical switch system for selectively inserting one of said networks between said transducer and said recording-reproducing head for recording signals derived from said transducer upon said windable element and for selectively inserting the other of said networks between said transducer and said recording-reproducing head for reproducing signals from said windable element into said transducer.

2. In a combined recorder-reproducer a removable magazine, said magazine comprising record spools with a windable magnetizable element, a recording-reproducing head and an erasing head mounted in operative relation to said element, a housing adapted to receive said magazine and comprising a driving means engageable into said spools, an electromechanical transducer, two electrical networks. differing in characteristics one from the other having their input terminals connectable to said transducer and having their output terminals connectable to said recordingreproducing head, a source of voltage connectable to said erasing head, and an electric switch system for connecting said source of voltage to said erasing head and simultaneously inserting one of said networks between said transducer and said recording-reproducin head, and for selectively inserting the other of said networks between said transducer and said recording-reproducing head and simultaneously disconnecting said source of voltage from said erasing head.

3. A magnetic reproducing device comprising a removable magazine and a housing adapted to receive the magazine, said magazine comprising a drum rotatably mounted on a shaft provided with a clutch member, a magnetic windable element wound upon said drum and adapted to be moved by the rotation of the shaft, a reproducing electromagnet and an erasing electromagnet mounted in operative relation to said element, said reproducing electromagnet and said erasing electromagnet being respectively connected to electrical terminals conveniently fastened to the walls of the magazine; said housing comprising a motor, a shaft driven by said motor and provided with a clutch member, an electromechanical transducer for translating sound waves into electrical voltages, electrical plugs conveniently located within said housing and connectable to the said transducer, a source of current, electrical plugs conveniently located within said housingelectromechanical transducer connected to said coil for translating sound waves into an electric current.

8. A magnetic recorder for magnetizing a wire to provide a sound record comprising two elongated low reluctance members disposed longitudinally in such a manner that the axis of one of said members forms the extension of the axis of the other member in a longitudinal direction, said members having their adjoining extremities separated by a high reluctance gap and having elongated longitudinal openings aligned with said axis whereby a wire to be magnetized can be moved longitudinally through said openings, tubular elements imbedded in said openings and surrounding said wire, a magnetic core member connecting the non-adjoining extremities of said members to provide a low reluctance magnetic path, a coil mounted in an operative relationship to said members for producing a, flux traversing said members in the direction of said axis, and an electromechanical transducer connected to said coil for translating sound waves into an electric current.

9. In a magnetic reproducer for reproducing sound from a magnetized wire, comprising two longitudinal magnetic core members aligned along the same axis and positioned with a pole piece o1 one and a pole piece of the other displaced one with respect to the other along the said axis whereby the planes of said pole pieces are perpendicular to said axis, said core members being provided with elongated openings along said .axis through which the magnetized wire is passed with the longitudinal dimension of said wire substantially aligned along said axis and at right angles to the planes of said pole pieces, a tubular element imbedded in said opening and surrounding said wire, said tubular element having a relatively low reluctance, a link element connecting said core members to provide a low reluctance magnetic path therebetween, a coil mounted in an operative relation ship with respect to said core members, and electrically actuated reproducer means connected with said coil to reproduce without distortion records of sound represented *by substantially longitudinal magnetization of said wire.

SERGE ALEXANDER SCHERBATSKOY.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,665,784 Hornauer Apr. 10, 1928 2,069,841 Massonneau Feb. 9, 1937 2,281,793 Patrick May 5, 1942 2,321,812 Heller June 15, 1943 2,351,003 Camras June 13, 1944 2,351,004 Camras June 13, 1944 2,351,005 Camras June 13, 1944 2,351,007 Camras June 13, 1944 2,359,489 Proctor Oct. 3, 1944 FOREIGN PATENTS Number Country Date 289,195 Great Britain Apr. 26, 1928 375,749 Germany May 18, 1923 

